The proposed study will examine the acceptability, feasibility, and preliminary efficacy of an HIV prevention program aiming to reduce stigma, transpobia, and HIV risk behaviors among kathoey (transwomen) sex workers (KSWs) in Bangkok, Thailand. High HIV sero-prevalence has been reported among kathoey in Bangkok and other large cities in Thailand. KSWs engage in substance use and HIV risk behaviors and are exposed to unique individual, cultural, and social factors that elevate their vulnerability for HIV infection (e.g., gender identity and hormone use). There is a huge gap in HIV prevention studies targeting KSWs, particularly addressing stigma and transphobia. PrEP is available in Thailand through designated hospitals and demonstration projects; however, few KSWs have enrolled in PrEP. We propose to develop an HIV prevention intervention curriculum based on our previous projects targeting transwomen in the U.S., examine the acceptability and feasibility, and evaluate the preliminary efficacy of a pilot intervention. The intervention will adapt principles from an empirically supported HIV prevention intervention: Motivational Enhancement Intervention (MEI) and will develop culturally appropriate and innovative HIV prevention programs for KSWs (e.g., delivering follow-up MEI sessions through cellphone and utilizing street vendors for recruitment). The study team consists of researchers at Chulalongkorn University, Bangkok and the Public Health Institute in the U.S., and has ample experience in HIV prevention for KSWs and is well-grounded in the targeted kathoey communities. The specific aims of the study are: 1) To adapt HIV prevention MEI protocols for use with KSWs, we will conduct iterative phases of formative research based on discussions with the kathoey community advisory board (CAB) members, local experts, and street vendors, and revise the protocol; 2) To further refine the intervention protocol, we will recruit 16 KSWs and conduct a preliminary assessment of the feasibility and acceptability of the protocol and further integrate feedback into the protocol; 3) To explore preliminary effects of our adapted MEI intervention and examine trial implementation procedures, we will randomly assign 120 KSWs to either MEI delivered by trained kathoey health educators (KHEs) or a health promotion information- only control group. We will examine our primary hypothesis that participants receiving MEI are more likely to reduce stigma, transphobia, and substance use and sexual risk behaviors and increase self-esteem, social support, and enroll in PrEP at follow-up assessments compared with the control group. Through process evaluation, we will examine intervention acceptability, feasibility, fidelity, and implementation of the trial procedures; such as recruitment, randomization, and follow-up retention. The proposed study will provide a solid foundation for preparing an R01 application to examine the efficacy of the HIV prevention intervention program with behavioral (MEI) and biomedical (PrEP) components targeting KSWs in Thailand who are at high risk for HIV and substance abuse, but have been neglected by HIV prevention programs in Thailand.